1. Field of the Invention
The invention relates to an ice storage element, especially for the auxiliary air conditioning system of a motor vehicle, with a hollow body for forming at least one storage space for an ice storage medium which is liquid in the thawed state and which can be brought into heat-conductive connection with a refrigerant.
2. Description of Related Art
Conventional ice storage elements of the above described type are provided with complex, and thus expensive, volume equalization elements, for example, of rubber or plastic, in order to ensure volume compensation of the ice storage medium which expands in a phase transition, e.g., freezing. The disadvantage in the known ice storage elements of the type under consideration is, moreover, that the thawed ice storage medium within the storage space of the ice storage element produces a sloshing noise while driving which is a nuisance, since it is perceived by the driver or passenger when the storage element is located in or directly against the passenger compartment.
Furthermore, an ice storage element known from published German Patent Application DE 35 31 158 A1 has a housing formed of a hollow polyethylene section into which metallic refrigerant pipelines are inserted and fixed relative to the walls by additional holding parts. Heat transfer from the cold storage medium within the housing to the air flowing past externally is poor due to the plastic housing. The refrigerant pipelines must be secured with additional components in a complex manner, due to which such an ice storage element is expensive to manufacture.
Therefore, the primary object of this invention is to devise a ice storage element which uses simple and economical means to withstand expansion of the ice storage medium in a phase transition/freezing without damage and which has an ice storage medium which does not produce sloshing noise in the thawed state.
This object is achieved by the ice storage medium containing a foaming or thickening agent in a quantity and quality such that sloshing of the ice storage medium in the thawed state is suppressed and freezing of the ice storage medium in the form of slush is ensured during at least one phase of volume expansion.
In other words, in accordance with the invention, the properties of the ice storage medium are modified such that, in the installed state, a foamy or gel-like consistency develops which prevents sloshing motion of the thawed medium. Moreover, the property of the ice storage medium is changed by the added foaming agent or thickening agent such that during freezing, i.e., in the transition from the liquid to the solid state, a slush is formed which ensures uniform expansion of the ice storage medium during freezing so that the wall of the storage space of the ice storage element is uniformly loaded and can withstand the volume expansion of the ice storage medium which is freezing. The slush which forms is comparable to crusted snow or finely crushed ice in terms of consistency.
Except for an air cushion which is conventionally provided in the storage space of the ice storage element, no additional volume equalization element is necessary by means of the measure according to the invention to freeze and thaw the ice storage medium in the closed, rigid storage container which forms the storage space. In addition, sloshing noise is reliably suppressed because the thawed ice storage medium is foamy or viscous such that it is too inert to slosh.
Advantageously, a water-based ice storage medium is used. The thickener added to the ice storage medium can, for example, be a gelling agent.
The thickening agent or gelling agent can be any known agent with this property which is matched to the ice storage medium used, which is, for example, preferably water-based. Advantageously, an inorganic agent with thickening or gelling properties is used as the thickening agent or gelling agent. Alternatively, an organic thickening agent can be used, for example, in the form of a polymer which is capable of swelling or in the form of a biological thickening agent.
Advantageously, the thickening agent can also be present in the form of a mixture of different thickening additives and/or foaming agents in order to acquire the desired consistency of the ice storage medium.
In the following the invention is detailed by way of example using the drawings.